Pattern component emitter



May 15, 1951 J. w. BRYcE T51-A1. 2,553,170

PATTERN COMPONENT EMITTER Filed April 27, 1948 3 sheets-sheet 1 lr-l H In INVENTORS n JCU/785 WB!" ce RobeffrB/a e/y BY 5 ATTORNEY May l5, 1951J. w. BRYcE ET AL 2,553,170

PATTERN COMPONENT EMITTER Filed April 27, 1948 3 Sheets-sheet 2 ATTORNEYMay 15, 1951 J. w. BRYCE ET AL 2,553,170

PATTERN COMPONENT EMITTER Filed April 27, 1948 3 Sheets-Sheet 3 ATTORNEY Patented May 15, 1951 PATTERN `COMPONENT EMITTER James W. Bryce,VGlen Ridge, N. J., and Robert T. Blakely, Amityville, N. Y., assignorsto International Business Machines Corporation, New York, N. Y., acorporation of New York Application April 27, 1948, Serial No. 23,564

7 claims. 1

This invention relates to improved control apparatus for controllingcharacter display by cathode ray tubes.

In United States Patents No-s. 2,264,623, 2,267,- 812 and 2,264,587 suchcontrol means was provided by a pattern component emitter which includedrotatable discs having light tracks thereon which were scanned byphoto-cells. The light tracks were coordinated with components ofcharacter outlines. The photo-cell means controlled amplifying meanswhich in turn applied controlling potential to the cathode ray characterdisplaying tubes.

According to the present invention the use of light tracks and scanningphoto-cells is dispensed with and in lieu thereof the rotatable patterncomponent emitter comprises .a capacity vchanging Ydevice which duringrotation provides changes in capacity which are related to the twocomponents of character outlines. The changes in capacity control thefrequency of oscillators. These oscillators in turn control the voltageoutput of frequency discrimina-tors. The frequency discriminators applytheir output voltage changes to the deiection .plates of cathode raytubes through amplifiers.

The present invention has for its general object the improvement of thepattern component emitter as described in the foregoing patents.

A further object vof the present invention resides in the provision ofan improved pattern component emitter wherein capacity change effectsare utilized for controlling character outlines.

A further'object of the present invention resides in the provision ofmeans for controlling character slant.

A further object resides in the provision of a pattern componentgenerator of electronic character .adapted to utilize capacity changeeffects and to convert capacity variation into voltage variationIthrough oscillator and frequency discriminator means.

In the drawings:

Fig. 1 is a top plan view .of the pattern component emitter unit withthe cover removed to show the parts beneath the cover;

Fig. 2 is a sectional View of the pattern component emitter unit, lthesection being taken onv line 2 2 of Fig. l;

Fig. 3 is a diagrammatic graph view, showing the plotting utilized forthe layout of a typical zero character;

Fig. 4 is an enlarged segment of one ofthe pattern component emitterdiscs;

Fig. 5 is a similar view of the related segmentv on the other disc; g

Fig. 6 is a circuit diagram showing the circuits of the apparatus up toand including the ampliner unit and with the output lines therefrom; and

Fig. 7 is a. diagrammatic showing of the effect of slant control on adisp-layed character.

The pattern compo-nent emitter which forms the subject-matter of thepresent invention is intended for use in systems of the type shown inBryce Patent No. 2,267,812, Dickinson Patent No. 2,254,623. and RothPatent No. 2,264,587. In all of these previous systems cathode raynumber displaying tubes were provided. These were supplied withcontrolling potentials through photo-cell controlled amplier units, oneunit being for the Y component potentials and the other unit for the Xcomponent potentials. Character selecting means were also provided andcommutator selecting devices, such as shown at 3S in Fig. 15A of theBryce patent, were also provided. ln the present application, thecommutator devices are retained and the amplifier units are shown on thecircuit diagram. For a description of other cooperating parts of thecompiete system, reference may be had to the abovementioned patents.

Referring now to Fig. l, the pattern component emitter unit is containedin a suitable box I0. Within the hoX is a suitably journaled shaft Il,adapted to be driven by a constantly running motor l2. Disposed on theshaft are a group of commutator selectors which are generally designatedi3, such commutator selectors correspond to commutator selectors 38shown in Fig. 15A of the Bryce patent. Also disposed on the shaft androtatable therewith, are a pair of rotatable metallic plates MY and MX.Each plate has adjacent its periphery and spaced` therefrom fixedmetallic plates IEX and |5Y.

Referring now to Figure 2, it will be noted that the plate lliY has .avariably notched peripheral portion. It will be appreciated that withone of the plates rotating the variable notched peripheral portion will,in cooperation with the fixed plates, provide variable overlapping areasduring rotation. This, in eii'ect, provides a Variable capacitydepending upon the amount of overlapping area of the periphery of therotatable plate with respect to the constant area of the fixed plate.

Plates and MY are preferably insulated from the shaft il and eachrotatable plate 'has adjacent thereto and rotatable therewith acommutator 36X or iEiY, made of conducting material i frequency willdecrease.

which is electrically connected to the plate. Cooperating with thecommutatore iX and NSY are brushes I'X and ilY.

Referring again to the nxed plates l5X and ISY, these plates arepreferably mounted on brackets such as ESX and iSY, adjustably securedto the base plate of the emitter housing. The adjustment will permitadjusting the gap between each fixed plate and its rotatable plate.

Referring now to Figure 2, it will be noted that the disc HEY is showndivided up Vinto successive segments or segment portions. The segmentportions of this disc have each been given a designating figure, such asd, l, 2, 3, il, 5, 6, 7, S and S. The segments of the related X discwould have like designating numbers. As briefly explained heretofore,the purpose of the varying contour of the periphery of the disc lllY isto provide for proper Variation of the condenser capacity. As eX#plained heretofore, the above-mentioned capacity is connected in anoscillator circuit and, as is well known in such circuits, the resonantfrequency is obtained from the equation:

f=the frequency in cycles per second Lzthe inductance inmicro-microhenries CY -.the capacity in micromicrofarad 1r=3.14l6-}-with L the inductance maintained at a constant value then the frequencyf is inversely proportional to the square root of the capacity C.

The capacity C is obtained from the equation:

In actual practice for this device two condensers are provided, one ofwhich is xed and retains the oscillator at a desired maximum frequency.The other is variable and comprises the overlap between, for example,the xed plate 55g and the rotating plate lily and varies the frequencybelow the desired maximum in a precise manner. Since the capacityvariation is small it Was found that having all the capacity in theseplates necessitated extreme accuracy in shaping the plate i411 since thepercentage area variation was small. By using the fixed condenser inparallel with the Variable Vernier shaping of the disc was found to beeasier.

lFrom the `foregoing it will be apparent that when a disc such as HiY isrotated the capacity and accordinglythe frequency of the oscillatoroutput will be changed. As capacity increases the This decrease in turnwill result in an increased voltage output which is fed through acustomary amplifier to the Y plates of the cathode ray tubes. Similarcontrols are provided for the X plates of the cathode ray tubes. Bychanging the potential on both sets of plates oi the cathode ray tubes,as fully de- (for example scribed in the above-mentioned patents, anyde-- sired character may be traced on the cathode ray tube screen.

The manner of laying out the disc segments will now be explained:

' It is known that as the frequency varies within certain limits fromabove resonance to beloaY 4 resonance the voltage output of a. frequencydiscriminator will vary from a negative to a posi tive value.

Referring now to Figure 3, this graph shows the character Zero laid out.The character has been divided up into a set of sections of equallength, this particular Vcharacter being divided into sections l to 135inclusive. In order to control tracing of an electron beam starting at land proceeding to l2, it will be noted that the Y component Voltagestarts at an intermediate Value and gradually increases to a maximum.

Referring now to Figure 4, 25 shows the contour of the Y plate for thesegment which is to control the Y component for the character 0. It willbe noted that the contour starts at a point S, remains constant to the lposition and then increases gradually until point i2 is reached.

Considering now the 0- portion of the MX disc (see Figure 3) the Xcomponent starts frorna il value at point l and gradually increases toonehalf its maximum value at point i2.

Referring now to Figure 5, it will be noted that the disc contour'gradually increases from a 0 value to one-half its maximum value at the12 position (note the contour line 26).

When the tracing beam is to be held station ary its related disc willhave a uniform contour. When the tracing beam is to change in height,the contour of the disc is progressively increased or decreased, as thecase may be. When the height increases, the beam on the cathode ray tubemoves either upwardly or to the right and when it decreases the beameither vmoves downwardly Vor to the left. The above of course applies toboth discs.

' To determine the height of the MY disc for a particular point on the 0character as, for example, point 42, the Y ordinate distance in Fig. 3is measured. This distance is used as a measure of the deflectionvoltage required on the cathode ray Y plates. From the graph Fig. 3 thisordinate value is seen to be 2 Volts. Using a resonant frequency of 4.3megacycles the corresponding operating frequency would then be:

where the 25,000 cycles corresponds to a potential of 2 Volts in adiscriminator circuit.

Substituting the above in Equation 1 with L: 1GO microhenries lan/icoxio-@XCXw-H l 2 41r2X100X10-5X4-275 C 13.86 micromicrofarads Withthe fixed capacity equal to 13.70 micromicrofarads the amount ofvariable capacity required is 13.86-13.70=0.16 m'icromicrofaradsSubstituting this value in Equation 2 to determine the area A=0. 17952sq. in.'

essaim lar Lpoint on the character is determined. .From the-discriminator curve the frequency corriesponding "to this `value -isdetermined.

Knowing this vfrequency the capacity lis kdetermined from Equation lusing L='10O microhenries.

From this determined capacity value the fixed capacity value of 13.70microm-icrofarads is subtracted to find the lamount of the variable4capacity. The superimposed area required to obtain this capacity isthen found from Equation 2. This area divided by the width of .2 in.will give the height of the overlap at the point under consideration.

Oscillator, discriminate/r und :amplifier circuits Before describing'the circuit diagram indetail, it may be mentioned that the variable Xplate, in conjunction with the `fixed X plate, and in furtherconjunction with a fixed condenser, controls an oscillator which may betermed an X oscillator 'and that the related variable Y plate, xed Yplate, and fixed condenser, controls another oscillator which may bevgenerally termed a Y oscillator. IIhe X oscillator in turn, through acoupling circuit, controls an X frequency discriminator, and the Yoscillator, through a similar coupling circuit, controls a Y `frequencydiscriminator. The output of the Y discriminator is fed to an Xamplifier. From the X .and Y amplifier units circuits lead off to theplates of the cathode ray number displaying tubes.

'Ihe X circuits will now be described. As shown in the circuit diagramFig. '6, the variable capacitance provided yby 14X and 15X is shun'tedby iixed capacitance 2. The combination of the capacitance UEX, lFsX,'21, inductances 28 and 29, capacitor S, resistor 3|, tube 32, condenser33, inductance 34, and battery 35 are connected in the well-knownHartley oscillator circuit. The output frequency of this oscillator isdependent upon the capacity of 'the l-X, 15X combination. This variablefrequency output is coupled by means of a capacitor 38, transformer 31.,to an amplilier tube 38. The output of this amplifier is coupled byinductances 39, Sto the input of a frequency discrim'inator circuit. Thefrequency discriminatory circuit includes an inductance 40, capacitorsand liti, capacitor dt, inductance dei, double diode tube e5, capacitors46 and :47, and -a resistor 48. The details and mode of operation ofthis frequency discriminator need not be further expiained sincereference may be had to A. R. R. L. Handbook, 1942 edition, page 142.

The lower end of a resistor 4S, which is across the output of thefrequency discriminator, is connected by means of a line 5E! andcontacts 'I8 and line lll to the cathode of an amplifier tube 5l. Theother end of this resistor 49 is connected to the grid of amplier tube5l. The plate cathode circuit of tube lX includes a B battery or othersource of direct current 52. A resistor 53 is disposed in seriesintermediate the positive side of the battery and the plate of tube 5IX.For impressing a proper voltage control across the horizontal deiiectingplates of the cathode ray tubes a biasing network is provided includinga resistor 54 connected across a source'` of voltage preferablycomprising series connectedli batteries 55 and 555. The conductorintermediate the batteries is also connected to a preliminary adjustabletap 5l' on resistor 53. The output lines E and Si are respectivelyconnected to a preliminary adjustable tap S on resistor 54 throughcontacts 16 and to the positive side of l by discriminator tube EE.

battery 52. These output lines BB and i6! c011- nect with terminals 62and 63. The said termina1s'52 'and 63 correspond to the terminals 58 and57 lin Bryce Patent No. 2,267,512 (see Fig. 15A). The X plates of thecathode ray number display tubes are Aconnected to these terminals andthe usual character selecting devices vare also provided as fullydescribed in 'the abovementioned Bryce patent.

It will be understood that the change in potential across terminals 52and 63 controls the deection of the electron beam in the cathode raytubes for the X component ci character display. This is fully kdescribedin the Bryce patent.

Having fully described the X oscillator, the X frequency discriminator,and the X amplifier, the description need not be repeated .for theYost-,illator, the Y frequency discriminator, andthe Y amplifier sincethe circuits .are identical. It is sumcient to state that the Yamplifier output circuits extend to terminals 512. and '65respectively., said terminals corresponding to terminals 66 and 67, asshown in Figure 15A Vof the Bryce patent.

Character slant control If it is desired to control the character slant,switch control handle 'l5 is shifted to reverse position to that shownin Fig. l. This will open contacts "i5, 'i3 and close contacts il and59. A cathode resistor 8B is provided in the cathode circuit of ampliertube MY. Connection from an adjustable contact a provides a cathodefollower connection through contacts 'i9 to the lower end of resistorISB via Wire 50.

As current flow is increased through amplier tube 5l Y this cathodefollower connection raises the potential at the lower end of resistor 49and augments the X potential normally applied This provides acorrespcndingly greater X potential as the Y potential is increased. Theultimate is that the displayed character has-a slant tothe right. 'Theamount of slant is controllable by varying the position of tap 80a.

yIn addition, the switching of contacts 15 and 'E1 places control of thecharacter `centering `under tap 13 so that, as the character is slanted.in it may be recentered for symmetry on the cathode ray tube screen.These effects are shown in Fig. 7. |14 represents in outline theconventional upright characterization of the character 4. Line '|75represents the angle of character slant, and at any abscissa value aspoint H6 the ordinate represents the increase over normal ordinatedistance which causes the character to slant. The dotted line whichincludes point ll'f represents the control effected by contact i8 andthe dot and dash line including point H5 represents the recenteringeffected by contact 11.

What is claimed is:

l. Control apparatus for controlling electron beams of a cathode raycharacter displaying device including in combination a pair of fixedplates, rotatable elements having a pair of plates shaped to providesuccessive variable overlapping areas representative of successivecharacter designations with respect to said fixed plates duringrotatie-n thereof, means for continuously rotating said rotatableelements, a pair of oscillators with the frequency thereof controlled byvariations in capacity induced by the rotatable elements when in motionpast the iixed plates, a pair of frequency discriminators coupled tosaid oscillators to provide variable voltage outputs, and meansresponsive to said outputs for controlling 7 the electron beams of thecathode ray displaying device.

2. Control apparatus for controlling the electron beams of a cathode raycharacter displaying device comprising capacity change inducing meansincluding fixed plates and cooperating continuously rotating platesshaped to provide variable overlapping areas with respect to the fixedplates upon rotation of the rotatable plates, a fixed capacitanceassociated with each of said capacity change inducing means, a pair ofoscillators controlled by the aforesaid capacity change inducing meansto produce frequencies which vary from a predetermined frequencycontrolled by said fixed capacitance in accordance with capacitythereof, a pair of frequency discriminators controlled by theoscillators to induce changes in potential corresponding to the changesin capacity and amplifying means controlled by the frequencydiscriminating means and afford-` ing output potentials for controllingthe electron beams, said rotatable plates having a configuration tocontrol tracing of the outlines of complete sets of different charactersupon each rotation of the rotatable plates.

3. A slant control for a cathode ray character displaying apparatuscomprising in combination a pair of voltage output amplifiers, one foran X component and another for a Y component means toV control theoutput potentials cf said amplifiers whereby the potential outputs arerepresentative of components of character outlines, a cathode resistorin the Y amplifier, and a oathode follower connection from said resistorto the input of the X amplifier to provide a correspondingly greater Xpotential as the Y potential is increased for the purpose described.

4. The inventionraccording to claim 3 wherein switching means areprovided to establish er break said cathode follower connection.

5. The invention according to claim 3 wherein recentering control meansare provided for recentering the displayed character.

6. A control apparatus for supplying variable potentials to amplifyingmeans in accordance with predetermined voltage variations, including incombination, a pair of frequency discriminators, one for each of twocomponents of the voltage, whichdiscriminators are coupled to theamplifying means to supply variable potentials thereto, a pair ofoscillators each of which supplies Variable frequencies to its relatedfrequency discriminator, means for varying the frequencies generated bythe oscillators from a predetermined frequency comprising capacitychange inducing means for each of the oscillators, each capacity changeinducing means including a fixed capacity plate anda rotatable capacityplate, each rotatable plate having a configuration shaped to providevariable areas of overlap with respect to the Xed plate upon rotation ofthe rotatable plate, said areas of each rotatable plate being shaped inaccordance with the related voltage component, said two voltagecomponents corresponding to the components of a character outline, and acommon driving means for the said rotatable capacity plates whereby thecomponent voltage variations are synchronized so thatV two synchronizedvoltage variations corresponding to the components of a characteroutline are generated.

7. An apparatus of the class described including in combination apattern component emitter unit comprising means to generate successivecapacity changes representative of the components of a succession ofdifferent characters, said emitter unit comprising a continuouslymovable plate means and fixed plate means, oscillating means controlledby the capacity changes of said emitter, frequency discriminating meanscontrolled by said oscillating means to produce a varying potentialoutput, and amplifying means controlled by said potential output forproviding variable potential amplitudes in accordance with changes incapacity generated by said continu-V ously movable plate means and xedplate means.

JAMES W. BRYCE. ROBERT T. BLAKELY.

CITED f The following references are of record in the le of this patent:

UNITED STATES PATENTS OTHER REFERENCES AIE'E Journal, Nov. 1947, NumberDisplay Using the Cathode Ray Tube by G. T. Baker (paper dated Oct. 16,1946) pp. 421-426.

